The present invention relates to an antiviral composition, in particular an anti-HIV composition and to methods of treating viral infections. 2. Background Information
A nucleoside class of antiviral agents, a prototype of which is AZT, is widely used in the clinical treatment of acquired immune deficiency syndrome (AIDS). AZT was initially selected for clinical use based upon an in vitro antiviral assay.
While extremely useful in antiviral therapy, AZT is limited by toxicity and a therapeutic index insufficient to make it adequate for therapy. Accordingly, new classes of antiviral agents to be used alone or in combination with AZT and other agents are urgently needed for effective antiviral therapy.
In the search for new antiviral agents, an extensive screening program to identify potential anti-AIDS and anticancer compounds from natural sources has been initiated [Boyd M. R.: In AIDS Etiology, Diagnosis, Treatment and Prevention, (DeVita V. T. Jr, Hellman S, Rosenberg S. A., eds.) Philadelphia: Lippincott, 1988, pp. 305-317]. Ongoing natural product collection projects are focusing on unusual or underexplored plant, marine and microbial resources.
As a part of this search, Homalanthus acuminatus, a small endemic tree of the primary forests of Samoa, and an important component of Samoan ethnopharmacology has been studied. Interviews with "taulasea", or Samoan healers, indicated that various parts of the plant are used to treat physical ailments. For example, the leaves are used in water infusions to treat back pain and abdominal swelling, the roots to suppress diarrhea and the stem wood to treat yellow fever [Cox P. A.: Samoan Ethnopharmacology. In Economic and Medicinal Plant Research, Vol. 4: Plants and Traditional Medicine. (Wagner H., Farnsworth N., eds.) London: Academic Press, in press]. Furthermore, related species are used in New Guinea (H. nervosus) to treat boils and sores [Holdsworth D. M.: Int. J. Crude Drug Res. 27:95-100, (1989)] and in Indonesia (H. nutans) for gonorrhea [Perry L. M.: Medicinal Plants of East and Southeast Asia. Cambridge: MIT Press, 1980, p. 149]. Also, the leaves of H. nutans have been used to treat circumcision wounds in Samoa [Uhe G.: Econ. Bot. 28:1-30, (1979)].
In the present invention, extracts of H. acuminatus are used to exert inhibitory effects against the human immunodeficiency virus (HIV-1), the causative agent of the AIDS.